Answer:
What do people spend a lot of money on every year, but never want to use?
What has 4 fingers and a thumb but isn't alive?
I have keys but no locks. I have space but no room. You can enter but canβt go outside. What am I?
What goes around the wood but never goes into the wood?
I am lighter than air but a hundred people cannot lift me. Careful! I am fragile!
No matter how little or how much you use me, you change me every month.